1. Field of the Invention
This invention relates to seals for reciprocal and rotary shafts.
2. Description of the Prior Art
Various seals for reciprocal shafts, in pumps, fans, compressors, agitators and the like are known. A common type of shaft seal consists of packing composed of fibers which are first woven, twisted or braided into strands, and then formed into coils, spirals or rings. Common materials used are asbestos fabric, braided and twisted asbestos, rubber and duck, flax, jute and metallic braids.
Packings are lubricated to facilitate installation and extend the life of the packing. Lack of lubrication causes packing to become hard and lose its resiliency, thus increasing friction, shortening packing life, and increasing operating costs. Various means are known for lubricating packing rings such as providing a lantern ring or permitting a small amount of leakage through the packing. Packing rings permit seals to be adjusted or replaced without disassembly of major components. However, the major disadvantage of packing type seals are the necessity for frequent adjustment and the quantity of fluid flow required to lubricate them.
Compression packing rings cut with bevel joints have been used. The bevel permits a certain amount of sliding action, thus absorbing a portion of ring expansion.